/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright (c) 2015-2016 EfficiOS Inc. and Linux Foundation
 * Copyright (c) 2015-2016 Philippe Proulx <pproulx@efficios.com>
 *
 * Babeltrace - CTF message iterator
 */

#ifndef CTF_MSG_ITER_H
#define CTF_MSG_ITER_H

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stddef.h>
#include <babeltrace2/babeltrace.h>
#include "common/macros.h"

#include "../metadata/ctf-meta.hpp"

/**
 * @file ctf-msg-iter.h
 *
 * CTF message iterator
 *
 * This is a common internal API used by CTF source plugins. It allows
 * one to get messages from a user-provided medium.
 */

/**
 * Medium operations status codes.  These use the same values as
 * libbabeltrace2.
 */
enum ctf_msg_iter_medium_status
{
    /**
     * End of file.
     *
     * The medium function called by the message iterator
     * function reached the end of the file.
     */
    CTF_MSG_ITER_MEDIUM_STATUS_EOF = 1,

    /**
     * There is no data available right now, try again later.
     */
    CTF_MSG_ITER_MEDIUM_STATUS_AGAIN = 11,

    /** General error. */
    CTF_MSG_ITER_MEDIUM_STATUS_ERROR = -1,

    /** Memory error. */
    CTF_MSG_ITER_MEDIUM_STATUS_MEMORY_ERROR = -12,

    /** Everything okay. */
    CTF_MSG_ITER_MEDIUM_STATUS_OK = 0,
};

/**
 * CTF message iterator API status code.
 */
enum ctf_msg_iter_status
{
    /**
     * End of file.
     *
     * The medium function called by the message iterator
     * function reached the end of the file.
     */
    CTF_MSG_ITER_STATUS_EOF = CTF_MSG_ITER_MEDIUM_STATUS_EOF,

    /**
     * There is no data available right now, try again later.
     *
     * Some condition resulted in the
     * ctf_msg_iter_medium_ops::request_bytes() user function not
     * having access to any data now. You should retry calling the
     * last called message iterator function once the situation
     * is resolved.
     */
    CTF_MSG_ITER_STATUS_AGAIN = CTF_MSG_ITER_MEDIUM_STATUS_AGAIN,

    /** General error. */
    CTF_MSG_ITER_STATUS_ERROR = CTF_MSG_ITER_MEDIUM_STATUS_ERROR,

    /** Memory error. */
    CTF_MSG_ITER_STATUS_MEMORY_ERROR = CTF_MSG_ITER_MEDIUM_STATUS_MEMORY_ERROR,

    /** Everything okay. */
    CTF_MSG_ITER_STATUS_OK = CTF_MSG_ITER_MEDIUM_STATUS_OK,
};

/**
 * Medium operations.
 *
 * Those user functions are called by the message iterator
 * functions to request medium actions.
 */
struct ctf_msg_iter_medium_ops
{
    /**
     * Returns the next byte buffer to be used by the binary file
     * reader to deserialize binary data.
     *
     * This function \em must be defined.
     *
     * The purpose of this function is to return a buffer of bytes
     * to the message iterator, of a maximum of \p request_sz
     * bytes. If this function cannot return a buffer of at least
     * \p request_sz bytes, it may return a smaller buffer. In
     * either cases, \p buffer_sz must be set to the returned buffer
     * size (in bytes).
     *
     * The returned buffer's ownership remains the medium, in that
     * it won't be freed by the message iterator functions. The
     * returned buffer won't be modified by the message
     * iterator functions either.
     *
     * When this function is called for the first time for a given
     * file, the offset within the file is considered to be 0. The
     * next times this function is called, the returned buffer's
     * byte offset within the complete file must be the previous
     * offset plus the last returned value of \p buffer_sz by this
     * medium.
     *
     * This function must return one of the following statuses:
     *
     *   - <b>#CTF_MSG_ITER_MEDIUM_STATUS_OK</b>: Everything
     *     is okay, i.e. \p buffer_sz is set to a positive value
     *     reflecting the number of available bytes in the buffer
     *     starting at the address written in \p buffer_addr.
     *   - <b>#CTF_MSG_ITER_MEDIUM_STATUS_AGAIN</b>: No data is
     *     available right now. In this case, the message
     *     iterator function called by the user returns
     *     #CTF_MSG_ITER_STATUS_AGAIN, and it is the user's
     *     responsibility to make sure enough data becomes available
     *     before calling the \em same message iterator
     *     function again to continue the decoding process.
     *   - <b>#CTF_MSG_ITER_MEDIUM_STATUS_EOF</b>: The end of
     *     the file was reached, and no more data will ever be
     *     available for this file. In this case, the message
     *     iterator function called by the user returns
     *     #CTF_MSG_ITER_STATUS_EOF. This must \em not be
     *     returned when returning at least one byte of data to the
     *     caller, i.e. this must be returned when there's
     *     absolutely nothing left; should the request size be
     *     larger than what's left in the file, this function must
     *     return what's left, setting \p buffer_sz to the number of
     *     remaining bytes, and return
     *     #CTF_MSG_ITER_MEDIUM_STATUS_EOF on the \em following
     *     call.
     *   - <b>#CTF_MSG_ITER_MEDIUM_STATUS_ERROR</b>: A fatal
     *     error occurred during this operation. In this case, the
     *     message iterator function called by the user returns
     *     #CTF_MSG_ITER_STATUS_ERROR.
     *
     * If #CTF_MSG_ITER_MEDIUM_STATUS_OK is not returned, the
     * values of \p buffer_sz and \p buffer_addr are \em ignored by
     * the caller.
     *
     * @param request_sz	Requested buffer size (bytes)
     * @param buffer_addr	Returned buffer address
     * @param buffer_sz	Returned buffer's size (bytes)
     * @param data		User data
     * @returns		Status code (see description above)
     */
    enum ctf_msg_iter_medium_status (*request_bytes)(size_t request_sz, uint8_t **buffer_addr,
                                                     size_t *buffer_sz, void *data);

    /**
     * Repositions the underlying stream's position.
     *
     * This *optional* method repositions the underlying stream
     * to a given absolute position in the medium.
     *
     * @param offset	Offset to use for the given directive
     * @param data		User data
     * @returns		One of #ctf_msg_iter_medium_status values
     */
    enum ctf_msg_iter_medium_status (*seek)(off_t offset, void *data);

    /**
     * Called when the message iterator wishes to inform the medium that it
     * is about to start a new packet.
     *
     * After the iterator has called switch_packet, the following call to
     * request_bytes must return the content at the start of the next
     * packet.	 */
    enum ctf_msg_iter_medium_status (*switch_packet)(void *data);

    /**
     * Returns a stream instance (weak reference) for the given
     * stream class.
     *
     * This is called after a packet header is read, and the
     * corresponding stream class is found by the message
     * iterator.
     *
     * @param stream_class	Stream class of the stream to get
     * @param stream_id	Stream (instance) ID of the stream
     *			to get (-1ULL if not available)
     * @param data		User data
     * @returns		Stream instance (weak reference) or
     *			\c NULL on error
     */
    bt_stream *(*borrow_stream)(bt_stream_class *stream_class, int64_t stream_id, void *data);
};

/** CTF message iterator. */
struct ctf_msg_iter;

/**
 * Creates a CTF message iterator.
 *
 * Upon successful completion, the reference count of \p trace is
 * incremented.
 *
 * @param trace			Trace to read
 * @param max_request_sz	Maximum buffer size, in bytes, to
 *				request to
 *				ctf_msg_iter_medium_ops::request_bytes()
 * 				at a time
 * @param medops		Medium operations
 * @param medops_data		User data (passed to medium operations)
 * @returns			New CTF message iterator on
 *				success, or \c NULL on error
 */
BT_HIDDEN
struct ctf_msg_iter *ctf_msg_iter_create(struct ctf_trace_class *tc, size_t max_request_sz,
                                         struct ctf_msg_iter_medium_ops medops, void *medops_data,
                                         bt_logging_level log_level, bt_self_component *self_comp,
                                         bt_self_message_iterator *self_msg_iter);

/**
 * Destroys a CTF message iterator, freeing all internal resources.
 *
 * The registered trace's reference count is decremented.
 *
 * @param msg_iter		CTF message iterator
 */
BT_HIDDEN
void ctf_msg_iter_destroy(struct ctf_msg_iter *msg_iter);

/**
 * Returns the next message from a CTF message iterator.
 *
 * Upon successful completion, #CTF_MSG_ITER_STATUS_OK is
 * returned, and the next message is written to \p msg.
 * In this case, the caller is responsible for calling
 * bt_message_put() on the returned message.
 *
 * If this function returns #CTF_MSG_ITER_STATUS_AGAIN, the caller
 * should make sure that data becomes available to its medium, and
 * call this function again, until another status is returned.
 *
 * @param msg_iter		CTF message iterator
 * @param message		Returned message if the function's
 *				return value is #CTF_MSG_ITER_STATUS_OK
 * @returns			One of #ctf_msg_iter_status values
 */
BT_HIDDEN
enum ctf_msg_iter_status ctf_msg_iter_get_next_message(struct ctf_msg_iter *msg_it,
                                                       const bt_message **message);

struct ctf_msg_iter_packet_properties
{
    int64_t exp_packet_total_size;
    int64_t exp_packet_content_size;
    uint64_t stream_class_id;
    int64_t data_stream_id;

    struct
    {
        uint64_t discarded_events;
        uint64_t packets;
        uint64_t beginning_clock;
        uint64_t end_clock;
    } snapshots;
};

BT_HIDDEN
enum ctf_msg_iter_status
ctf_msg_iter_get_packet_properties(struct ctf_msg_iter *msg_it,
                                   struct ctf_msg_iter_packet_properties *props);

BT_HIDDEN
enum ctf_msg_iter_status
ctf_msg_iter_curr_packet_first_event_clock_snapshot(struct ctf_msg_iter *msg_it,
                                                    uint64_t *first_event_cs);

BT_HIDDEN
enum ctf_msg_iter_status
ctf_msg_iter_curr_packet_last_event_clock_snapshot(struct ctf_msg_iter *msg_it,
                                                   uint64_t *last_event_cs);

BT_HIDDEN
enum ctf_msg_iter_status ctf_msg_iter_seek(struct ctf_msg_iter *msg_it, off_t offset);

/*
 * Resets the iterator so that the next requested medium bytes are
 * assumed to be the first bytes of a new stream. Depending on
 * ctf_msg_iter_set_emit_stream_beginning_message(), the first message
 * which this iterator emits after calling ctf_msg_iter_reset() is of
 * type `CTF_MESSAGE_TYPE_STREAM_BEGINNING`.
 */
BT_HIDDEN
void ctf_msg_iter_reset(struct ctf_msg_iter *msg_it);

/*
 * Like ctf_msg_iter_reset(), but preserves stream-dependent state.
 */
BT_HIDDEN
void ctf_msg_iter_reset_for_next_stream_file(struct ctf_msg_iter *msg_it);

BT_HIDDEN
void ctf_msg_iter_set_dry_run(struct ctf_msg_iter *msg_it, bool val);

static inline const char *ctf_msg_iter_medium_status_string(enum ctf_msg_iter_medium_status status)
{
    switch (status) {
    case CTF_MSG_ITER_MEDIUM_STATUS_EOF:
        return "EOF";
    case CTF_MSG_ITER_MEDIUM_STATUS_AGAIN:
        return "AGAIN";
    case CTF_MSG_ITER_MEDIUM_STATUS_ERROR:
        return "ERROR";
    case CTF_MSG_ITER_MEDIUM_STATUS_MEMORY_ERROR:
        return "MEMORY_ERROR";
    case CTF_MSG_ITER_MEDIUM_STATUS_OK:
        return "OK";
    }

    bt_common_abort();
}

static inline const char *ctf_msg_iter_status_string(enum ctf_msg_iter_status status)
{
    switch (status) {
    case CTF_MSG_ITER_STATUS_EOF:
        return "EOF";
    case CTF_MSG_ITER_STATUS_AGAIN:
        return "AGAIN";
    case CTF_MSG_ITER_STATUS_ERROR:
        return "ERROR";
    case CTF_MSG_ITER_STATUS_MEMORY_ERROR:
        return "MEMORY_ERROR";
    case CTF_MSG_ITER_STATUS_OK:
        return "OK";
    }

    bt_common_abort();
}

#endif /* CTF_MSG_ITER_H */
